Method for discriminating between unicast device to device(d2d) communication and groupcast d2d communication

ABSTRACT

Embodiments herein disclose a method for identifying a unicast Device to Device (D2D) communication. Further, the method includes generating, by a source User Equipment (UE), a D2D Media Access Control (MAC) Protocol Data Unit (PDU) comprising a unicast parameter. Further, the method includes transmitting, by the source UE, the D2D MAC PDU to the destination UE. Further, the method includes receiving, by the destination UE, the D2D MAC PDU. Further, the method includes detecting, by the destination UE, one of unicast parameters and groupcast parameters of the D2D MAC PDU. Furthermore, the method includes identifying, by the UE, the D2D MAC PDU is for one of the unicast D2D communication when the unicast parameters are detected, and the groupcast D2D communication when the groupcast parameters are detected.

CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY

The present application claims priority under 35 U.S.C. § 365 toInternational Patent Application No. PCT/KR2016/001855 filed on Feb. 25,2016, entitled “METHOD FOR DISCRIMINATING BETWEEN UNICAST DEVICE TODEVICE (D2D) COMMUNICATION AND GROUPCAST D2D COMMUNICATION”, and throughIndian Patent Application No. 927/CHE/2015, which was filed on Feb. 26,2015, and Indian Patent Application No. 927/CHE/2015, which was filed onFeb. 18, 2016, each of which are incorporated herein by reference intothe present disclosure as if fully set forth herein.

TECHNICAL FIELD

The present embodiments relate to a wireless communication system, andmore particularly to a mechanism for discriminating between a unicastdevice to device (D2D) communication and a groupcast D2D communication.The present application is based on, and claims priority from an IndianApplication Number 927/CHE/2015 filed on 26 Feb. 2015, the disclosure ofwhich is hereby incorporated by reference herein.

BACKGROUND

Device to Device (D2D) communication is being studied in communicationstandard groups to enable data communication services between UserEquipment's (UEs). During the D2D communication a transmitting D2D UE(i.e., source UE) can transmit data packets to a group of D2D UEs (i.e.,destination UE) or broadcast data packets to all the D2D UEs. The D2Dcommunication between a transmitter and receiver(s) is connectionless innature (i.e. there is no connection setup (or no control messages areexchanged) between the transmitter and a receiver) before thetransmitter starts transmitting the data packets. During thetransmission, the transmitter includes source identification (ID) anddestination ID in the data packets. The source ID is set to the UE ID ofthe transmitter. The destination ID is the intended recipient of thetransmitted packet. The destination ID indicates whether the packet is abroadcast packet or a packet intended for a group. The destination IDfor broadcast is an ID reserved from group IDs. The UE is assigned a D2DUE ID for its associated group.

A D2D Media Access Control (MAC) Protocol Data Unit (PDU) for carryingone or more MAC Service Data Units (SDUs) for the D2D communicationincludes a MAC header and a MAC payload. The payload comprises of one ormore MAC SDUs corresponding to same destination i.e. group or broadcast.The source (SRC) field in the MAC header is set to D2D UE identifier(ID) of the source. The D2D UE ID is unique within the group i.e. eachmember of the group has distinct D2D UE ID. The destination (DST) fieldin the MAC header is set to 16 most significant bits (MSBs) of 24 bitD2D Layer-2 group ID of the destination group. The 8 least significantbits (LSBs) of 24 bit D2D Layer-2 group ID is transmitted in SchedulingAssignment (SA) or Scheduling Control (SC) information. The SA or SCinformation is transmitted prior to transmission of D2D MAC PDU. Thecurrent D2D MAC PDU format does not support a unicast D2D communicationi.e., D2D MAC PDU cannot be addressed to a destination UE.

SUMMARY

Currently, the D2D UE ID is only unique within the group. So that, theD2D UE ID of two UEs belonging to different groups can be same. Also,the D2D UE ID and D2D Layer-2 group ID can also be same. If the unicastD2D MAC PDU destined to the UE is sent by setting the destinationLayer-2 ID field in the MAC header to D2D UE ID then:

The D2D MAC PDU will be processed by another UE whose D2D UE ID is sameas the D2D UE ID in the DST field of the D2D MAC PDU. The D2D MAC PDUwill be wrongly processed by members of group whose group ID is same asthe D2D UE ID in the DST field of the D2D MAC PDU. The D2D MAC PDUaddressed to the D2D UE ID is wrongly processed by the UE as the D2D MACPDU addressed to the D2D Layer 2 group ID if the D2D Layer 2 Group IDand the D2D UE ID of the UE are same.

Thus, it is desired to address the above mentioned disadvantages orother shortcomings or at least provide a useful alternative.

The embodiments herein achieve a method for discriminating between aunicast D2D communication and a groupcast D2D communication. The methodincludes receiving, by a User Equipment (UE), a D2D Media Access Control(MAC) Protocol Data Unit (PDU). Further, the method includes detecting,by the UE, one of unicast parameters and groupcast parameters of the D2DMAC PDU. Furthermore, the method includes identifying, by the UE, theD2D MAC PDU is for one of the unicast D2D communication when the unicastparameters are detected, and the groupcast D2D communication when thegroupcast parameters are detected.

In an embodiment, the unicast parameter includes at least one of aunicast D2D MAC PDU format version, a unicast packet indicator, ascrambled Cyclic Redundancy Check (CRC) of a Scheduling Assignment (SA),a number of bits, values, size associated with at least one of anidentifier of a source UE, a group identifier of a source UE, and anidentifier of a destination UE.

In an embodiment, the groupcast parameter includes at least one of agroupcast D2D MAC PDU format version, an unscrambled CRC of the SA, thenumber of bits, values, size associated with at least one of anidentifier of the source UE, a group identifier of the source UE, and anidentifier of the destination UE.

In an embodiment, the D2D MAC PDU, for the unicast D2D communication,includes the unicast D2D MAC PDU format version, reserved bits, theidentifier of the source UE, a unicast identifier of the destination UE,MAC sub-headers, and a unicast MAC Service Data Unit (SDU).

In an embodiment, the D2D MAC PDU, for the unicast D2D communication,includes the unicast D2D MAC PDU format version, reserved bits having aunicast packet indicator, an identifier of the source UE, the unicastidentifier of the destination UE, the MAC sub-headers, and the unicastMAC SDU.

In an embodiment, the D2D MAC PDU, for the unicast D2D communicationacross groups, includes at least one of the unicast D2D MAC PDU formatversion, the reserved bits, the identifier of the source UE, the groupidentifier of the source UE, the unicast identifier of the destinationUE, the group identifier of the destination UE, the MAC sub-headers, andthe unicast MAC SDU.

In an embodiment, the D2D MAC PDU, for the unicast D2D communicationwithin a group, includes at least one of the unicast D2D MAC PDU formatversion, the reserved bits, the identifier of the source UE, the unicastidentifier of the destination UE, the group identifier of thedestination UE, the MAC sub-headers, and the unicast MAC SDU.

In an embodiment, the D2D MAC PDU, for the unicast D2D communication forone of within the group and across the groups, includes at least one ofthe unicast D2D MAC PDU format version, the reserved bits including thegroup identifier, the identifier of the source UE, the unicastidentifier of the destination UE, the group identifier of thedestination UE, the MAC sub-headers, and the unicast MAC SDU.

In an embodiment, the D2D MAC PDU, for the groupcast D2D communication,includes at least one of a groupcast D2D MAC PDU format version, thereserved bits, the identifier of the source UE, the group identifier ofthe source UE, the identifier of the destination UE, a groupcastidentifier of the destination UE, the MAC sub-headers, and a groupcastMAC SDU.

The embodiments herein achieve a method for identifying a unicast D2Dcommunication. The method includes generating, by a source UserEquipment (UE), a D2D Media Access Control (MAC) Protocol Data Unit(PDU) including a unicast parameter to identify the D2D MAC PDU for theunicast D2D communication at a destination UE. Further, the methodincludes transmitting, by the source UE, the D2D MAC PDU to thedestination UE.

The embodiments herein achieve a User Equipment (UE) for discriminatingbetween a unicast D2D communication and a groupcast D2D communication.The UE is configured to receive a D2D Media Access Control (MAC)Protocol Data Unit (PDU) and detect one of unicast parameters andgroupcast parameters of the D2D MAC PDU. Further, the UE is configuredto identify that the D2D MAC PDU is for one of the unicast D2Dcommunication when the unicast parameters are detected, and thegroupcast D2D communication when the groupcast parameters are detected.

The embodiments herein achieve a User Equipment (UE) for identifying aunicast D2D communication. The UE is configured to generate a D2D MediaAccess Control (MAC) Protocol Data Unit (PDU) including a unicastparameter to identify the D2D MAC PDU for the unicast D2D communicationat a destination UE. Further, the UE is configured to transmit the D2DMAC PDU to the destination UE.

The embodiments herein provide a computer program product including acomputer executable program code recorded on a computer readablenon-transitory storage medium. The computer executable program code whenexecuted causing the actions including receiving, by a User Equipment(UE), a D2D Media Access Control (MAC) Protocol Data Unit (PDU). Thecomputer executable program code when executed causing the actionsincluding detecting, by the UE, one of unicast parameters and groupcastparameters of the D2D MAC PDU. The computer executable program code whenexecuted causing the actions including identifying, by the UE, the D2DMAC PDU is for one of the unicast D2D communication when the unicastparameters are detected, and the groupcast D2D communication when thegroupcast parameters are detected.

The embodiments herein provides a computer program product including acomputer executable program code recorded on a computer readablenon-transitory storage medium. The computer executable program code whenexecuted causing the actions including generating, by a source UserEquipment (UE), a D2D Media Access Control (MAC) Protocol Data Unit(PDU) including a unicast parameter to identify the D2D MAC PDU for theunicast D2D communication at a destination UE. The computer executableprogram code when executed causing the actions including transmitting,by the source UE, the D2D MAC PDU to the destination UE.

These and other aspects of the embodiments herein will be betterappreciated and understood when considered in conjunction with thefollowing description and the accompanying drawings. It should beunderstood, however, that the following descriptions, while indicatingpreferred embodiments and numerous specific details thereof, are givenby way of illustration and not of limitation. Many changes andmodifications may be made within the scope of the embodiments hereinwithout departing from the spirit thereof, and the embodiments hereininclude all such modifications.

This disclosure provides a method for discriminating between a unicastDevice to Device (D2D) communication and a groupcast D2D communication.According to the method provided by the present disclosure, effectivediscrimination between a unicast Device to Device (D2D) communicationand a groupcast D2D communication is possible.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention is illustrated in the accompanying drawings, throughoutwhich like reference letters indicate corresponding parts in the variousfigures. The embodiments herein will be better understood from thefollowing description with reference to the drawings, in which:

FIG. 1 is a block diagram illustrating a protocol stack for a Device toDevice (D2D) communication, according to an embodiment as disclosedherein;

FIG. 2 is a block diagram illustrating various units of a source UserEquipment (UE), according to an embodiment as disclosed herein;

FIG. 3 is a block diagram illustrating various units of a destinationUE, according to an embodiment as disclosed herein;

FIG. 4a is a flow diagram illustrating a method for generating andtransmitting a D2D Media Access Control (MAC) Protocol Data Unit (PDU)at a source UE, according to an embodiment as disclosed herein;

FIG. 4b is a flow diagram illustrating a method for discriminatingbetween a unicast D2D communication and a groupcast D2D communication ata destination UE, according to an embodiment as disclosed herein;

FIG. 5a is a flow diagram illustrating source UE operations for D2D MACPDU generation and transmission which includes one of unicast parametersand groupcast parameters, according to an embodiment as disclosedherein;

FIG. 5b to FIG. 5d illustrate an example of a D2D MAC PDU format asdescribed in the FIG. 5a , according to an embodiment as disclosedherein;

FIG. 5e is a flow diagram illustrating destination UE operations fordiscriminating between a unicast D2D communication and a groupcast D2Dcommunication based on a D2D MAC PDU format version, according to anembodiment as disclosed herein;

FIG. 5f is a flow diagram illustrating destination UE operations fordiscriminating between a unicast D2D communication and a groupcast D2Dcommunication based on a Cyclic Redundancy Check (CRC) of SchedulingAssignment (SA)/Scheduling Control (SC), according to an embodiment asdisclosed herein;

FIG. 6a is a flow diagram illustrating source UE operations for D2D MACPDU generation and transmission which includes an unicast packetindicator, according to an embodiment as disclosed herein;

FIG. 6b to FIG. 6d illustrate an example of a D2D MAC PDU format asdescribed in the FIG. 6a , according to an embodiment as disclosedherein;

FIG. 6e is a flow diagram illustrating destination UE operations whilediscriminating a unicast D2D communication and a groupcast D2Dcommunication using a unicast packet indicator, according to anembodiment as disclosed herein;

FIGS. 7a and 7b illustrate an example of a D2D MAC PDU format forunicast across groups, according to an embodiment as disclosed herein;

FIGS. 8a and 8b illustrate an example of a D2D MAC PDU format forunicast across groups, according to an embodiment as disclosed herein;

FIGS. 9a and 9b illustrate an example of a D2D MAC PDU format forunicast within group or across groups, according to an embodiment asdisclosed herein;

FIG. 10a illustrates a process for partitioning a N bit address spacefor generating a D2D MAC PDU format, according to an embodiment asdisclosed herein;

FIG. 10b illustrates an example of a D2D MAC PDU format for unicastacross groups, according to an embodiment as disclosed herein;

FIG. 10c illustrates an example of a D2D MAC PDU for unicast withingroup, according to an embodiment as disclosed herein;

FIG. 10d illustrates an example of a D2D MAC PDU format for unicastacross groups, according to an embodiment as disclosed herein; and

FIG. 11 illustrates a computing environment implementing the mechanismfor discriminating a unicast D2D communication and a groupcast D2Dcommunication in a D2D communication, according to an embodiment asdisclosed herein.

DETAILED DESCRIPTION

The embodiments herein and the various features and advantageous detailsthereof are explained more fully with reference to the non-limitingembodiments that are illustrated in the accompanying drawings anddetailed in the following description. Descriptions of well-knowncomponents and processing techniques are omitted so as to notunnecessarily obscure the embodiments herein. Also, the variousembodiments described herein are not necessarily mutually exclusive, assome embodiments can be combined with one or more other embodiments toform new embodiments. The term “or” as used herein, refers to anon-exclusive or, unless otherwise indicated. The examples used hereinare intended merely to facilitate an understanding of ways in which theembodiments herein can be practiced and to further enable those skilledin the art to practice the embodiments herein. Accordingly, the examplesshould not be construed as limiting the scope of the embodiments herein.

The embodiments herein disclose a method for discriminating between aDevice to Device (D2D) unicast D2D communication and a groupcast D2Dcommunication. The method includes receiving, by a User Equipment (UE),a D2D Media Access Control (MAC) Protocol Data Unit (PDU). Further, themethod includes detecting, by the UE, one of unicast parameters andgroupcast parameters of the D2D MAC PDU. Furthermore, the methodincludes identifying, by the UE, the D2D MAC PDU is for one of theunicast D2D communication when the unicast parameters are detected, andthe groupcast D2D communication when the groupcast parameters aredetected.

The embodiments herein disclose a method for identifying a unicast D2Dcommunication and groupcast D2D communication. The method includesgenerating, by a source User Equipment (UE), a D2D MAC PDU including aunicast parameter to identify the D2D MAC PDU for the unicast D2Dcommunication at a destination UE. The method includes generating, bythe source UE, the D2D MAC PDU including a groupcast parameter toidentify the D2D MAC PDU for the groupcast D2D communication at thedestination UE. Further, the method includes transmitting, by the sourceUE, the D2D MAC PDU to the destination UE.

Unlike the conventional systems and methods, the proposed methodindicates whether the D2D MAC PDU carries the unicast or groupcast MACSDUs using distinct values of the D2D MAC PDU format version number. Theproposed method indicates whether the destination field in MAC header ofD2D MAC PDU is a unicast identifier or a group identifier using thedistinct values of the D2D MAC PDU format version number. The proposedmethod indicates whether the source field in the MAC header of D2D MACPDU is the D2D UE identifier for the D2D unicast communication or theD2D groupcast communication using the distinct values of the D2D MAC PDUformat version number. The proposed method can be used to indicatewhether the D2D MAC PDU carries the unicast or groupcast MAC SDUs usinga scrambled and unscrambled Cyclic Redundancy Check (CRC) of aScheduling Assignment (SA) (i.e., scrambled CRC using a predefined CRCmask for the SA corresponding to the unicast D2D MAC PDU and unscrambledCRC for the SA corresponding to a non-unicast D2D MAC PDU). The proposedmethod indicates whether the destination field in the MAC header of theD2D MAC PDU is the unicast identifier or the group identifier using ascrambled and unscrambled Cyclic Redundancy Check (CRC) of a SchedulingAssignment (SA) (i.e., scrambled CRC using a predefined CRC mask for theSA corresponding to the unicast D2D MAC PDU and unscrambled CRC for theSA corresponding to a non-unicast D2D MAC PDU). The proposed methodindicates whether the source field in the MAC header of the D2D MAC PDUis a D2D UE identifier for the D2D unicast communication or the D2Dgroup cast communication using the scrambled and unscrambled CRC of theSA (i.e., scrambled CRC using a predefined CRC mask for the SAcorresponding to the unicast D2D MAC PDU and unscrambled CRC for the SAcorresponding to a non-unicast D2D MAC PDU).The proposed method can beused to encode or decode the different values and sizes in a source(SRC) field/destination (DST) field of MAC header depending on whetherthe D2D MAC PDU carries unicast or groupcast MAC SDUs. The proposedmethod avoids the collision between the D2D UE ID and the D2D Layer-2group ID. The proposed method avoids the collision between D2D UE ID oftwo UEs.

The proposed method can be used to indicate whether the D2D MAC PDUcarries the unicast MAC SDUs using D2D MAC PDU format version number andunicast Packet Indicator (UPI). The proposed method can be used toindicate whether the D2D MAC PDU carries the unicast MAC SDUs using theunicast packet indicator and the scrambled CRC of the SA information(i.e., scrambled CRC using predefined CRC mask for the SA correspondingto the unicast D2D MAC PDU and the unscrambled CRC for the SAcorresponding to the non-unicast D2D MAC PDU). The proposed method canbe used to encode /decode of the SRC/DST UE ID/DST fields in case of theunicast D2D MAC PDU and encode/decode the SRC/DST fields in case ofnon-unicast D2D MAC PDU. The proposed method avoids the collisionbetween the D2D UE ID and the D2D Layer-2 group ID. The proposed methodcan be used to avoid the collision between D2D UE ID of two UEs.

For example, the MAC PDU format version number field indicates whichversion of a Sidelink Shared Channel (SL-SCH) subheader is used. In thisversion of the specification two format versions are defined, and thisfield shall therefore be set to “0001” or “0010”. The V field size is 4bits. SRC: The Source Layer-2 ID field carries the identity of thesource. It is set to the ProSe UE ID. The SRC field size is 24 bits. Ifthe V field is set to “0001” this identifier is the groupcastidentifier. If the V field is set to “0010” this identifier is a unicastidentifier. DST: The DST field carries the 16 most significant bits ofthe Destination Layer-2 ID. The Destination Layer-2 ID is set to theProSe Layer-2 Group ID or ProSe UE ID. If the V field is set to “0001”this identifier is the groupcast identifier. If the V field is set to“0010” this identifier is the unicast identifier.

Further, the proposed method can be used to determine the presence ofthe unicast packet indicator field in the MAC header using the D2D MACPDU format version number or the scrambled CRC of the SA. The proposedmethod can be used to encode/decode the different values and sizes inthe SRC/DST fields of the MAC header depending on whether the D2D MACPDU carries unicast or groupcast MAC SDUs.

Referring now to the drawings and more particularly to FIGS. 1 through11, where similar reference characters denote corresponding featuresconsistently throughout the figure, there are shown preferredembodiments.

The protocol stack for a device to device (D2D) communication isillustrated in the FIG. 1. A Packet Data Convergence Protocol (PDCP)layer in a communication unit 202 receives data packets i.e. internetprotocol (IP) packets (i.e., PDCP Service Data Unit (SDU)) from an upperlayer. It secures the packet and also compresses the IP headers. Theprocessed packet (i.e., PDCP Protocol Data Unit (PDU)) is sent to aRadio Link Control (RLC) layer. The RLC layer receives the PDCP PDUs(i.e., RLC SDUs) from the PDCP layer. It fragments the PDCP PDUs ifneeded and sends the RLC PDUs to a D2D Media Access Control (MAC) layer.The MAC layer multiplexes the RLC PDUs (or MAC SDUs) and sends the D2DMAC PDU to a physical (PHY) layer for transmission on a wireless channel(e.g. PC5 interface or the like).

The D2D MAC PDU for carrying the MAC SDU(s) for the D2D communicationincludes of the MAC header and a MAC payload. The payload comprises ofone or more MAC SDUs corresponding to same destination i.e. group orbroadcast. There exists one sub-header in the MAC header correspondingto each MAC SDU in the MAC payload. The subheader indicates the lengthof the MAC SDU and logical channel ID (LCID) of logical channelassociated with the MAC SDU. A D2D MAC PDU format version number fieldis also included in the MAC header. It is set to value one (i.e., in thebinary form 0001). In an embodiment, it is set to value two (i.e., inthe binary form 0010). The D2D MAC PDU format version number is includedin every D2D MAC PDU transmitted. It is present at the beginning of theD2D MAC PDU header.

In an embodiment, the MAC PDU format version number field indicateswhich version of a Sidelink Shared Channel (SL-SCH) subheader is used.In this version of the specification two format versions are defined,and this field shall therefore be set to “0001” or “0010”. The V fieldsize is 4 bits. SRC: The Source Layer-2 ID field carries the identity ofthe source. It is set to the ProSe UE ID. The SRC field size is 24 bits.If the V field is set to “0001” this identifier is the groupcastidentifier. If the V field is set to “0010” this identifier is a unicastidentifier. DST: The DST field carries the 16 most significant bits ofthe Destination Layer-2 ID. The Destination Layer-2 ID is set to theProSe Layer-2 Group ID or ProSe UE ID. If the V field is set to “0001”this identifier is the groupcast identifier. If the V field is set to“0010” this identifier is the unicast identifier.

FIG. 2 is a block diagram illustrating various units of a source UserEquipment (UE) 102, according to an embodiment as disclosed herein. Inan embodiment, the source UE 102 includes a communication unit 202, aprocessor unit 204, and a storage unit 206. The source UE 102 can be,for example, a cellular phone, a smart phone, a session initiationprotocol (SIP) phone, a satellite radio, a laptop, a personal digitalassistant (PDA), a video device, a global positioning system, a gameconsole, a multimedia device, a tablet, or any other similar functioningdevice. The source UE 102 may also be referred to by those skilled inthe art as a mobile station, a subscriber station, a mobile unit, asubscriber unit, a wireless unit, a remote unit, a mobile device, awireless device, a wireless communications device, a remote device, amobile subscriber station, an access terminal, a mobile terminal, awireless terminal, a remote terminal, a handset, a user agent, a mobileclient, a client, or the like. The communication unit 202 is providedwith the processor unit 204. The processor unit 204 is configured to seta D2D MAC PDU format version number in the MAC header of the D2D MAC PDUwherein the D2D MAC PDU format version number is set to different valuefor unicast and groupcast D2D communication. In an example, the 4 bitsD2D MAC PDU format version number is set to ‘0010’ (i.e., decimal value2) in the MAC header of the D2D MAC PDU for the unicast D2Dcommunication and the 4 bits D2D MAC PDU format version number is set to‘0001’ (i.e., decimal value 1) in the MAC header of the D2D MAC PDU forthe groupcast D2D communication.

In an embodiment, for the unicast D2D communication, the processor unit204 is configured to set DST field in the MAC header of D2D MAC PDU to16 MSBs of D2D UE ID of a destination UE (not shown). In anotherembodiment, the processor unit 204 is configured to set DST field in theMAC header of the D2D MAC PDU to 24 MSBs of the D2D UE ID of thedestination UE. In an embodiment, the processor unit 204 is configuredto set 24 bit SRC field in the MAC header of the D2D MAC PDU to its D2DUE ID. In another embodiment, the processor unit 204 is configured toset 32 bit SRC field in the MAC header of the D2D MAC PDU to the its D2DUE ID. Further, the processor unit 204 is configured to set a unicastPacket Indicator (UPI) field in the MAC header of the D2D MAC PDU andset UPI field to one. Further, the processor unit 204 is configured toset the MAC sub-header(s) in the MAC header corresponding to the MACSDU(s) in the D2D MAC PDU payload.

In an embodiment, for the groupcast D2D communication, the processorunit 204 is configured to set the DST field in the MAC header to 16 MSBsof the D2D Laye-2 Group ID of the destination UE. Further, the processorunit 204 is configured to set 24 bit SRC field in the MAC header to theD2D UE ID of the source UE 102. Further, the processor unit 204 isconfigured to set the MAC sub-header(s) in the MAC header correspondingto the MAC SDU(s) in the D2D MAC PDU payload.

Further, the processor unit 204 is configured to generate the D2D MACPDU having the unicast parameter and groupcast parameter. Aftergenerating the D2D MAC PDU including the unicast parameter and groupcastparameter, the communication unit 202 is configured to transmit the D2DMAC PDU to the destination UE.

In an embodiment, the MAC PDU format version number field indicateswhich version of a Sidelink Shared Channel (SL-SCH) subheader is used.In this version of the specification two format versions are defined,and this field shall therefore be set to “0001” or “0010”. The V fieldsize is 4 bits. SRC: The Source Layer-2 ID field carries the identity ofthe source. It is set to the ProSe UE ID. The SRC field size is 24 bits.If the V field is set to “0001” this identifier is the groupcastidentifier. If the V field is set to “0010” this identifier is a unicastidentifier. DST: The DST field carries the 16 most significant bits ofthe Destination Layer-2 ID. The Destination Layer-2 ID is set to theProSe Layer-2 Group ID or ProSe UE ID. If the V field is set to “0001”this identifier is the groupcast identifier. If the V field is set to“0010” this identifier is the unicast identifier.

The communication unit 202 is configured for communicating internallybetween internal units and with external devices via one or morenetworks. The storage unit 206 may include one or more computer-readablestorage media. The storage unit 206 may include non-volatile storageelements. Examples of such non-volatile storage elements may includemagnetic hard disc, optical discs, floppy discs, flash memories, orforms of electrically programmable memories (EPROM) or electricallyerasable and programmable (EEPROM) memories. In addition, the storageunit 206 may, in some examples, be considered a non-transitory storagemedium. The term “non-transitory” may indicate that the storage mediumis not embodied in a carrier wave or a propagated signal. However, theterm “non-transitory” should not be interpreted that the storage unit206 is non-movable. In some examples, the storage unit 206 can beconfigured to store larger amounts of information than a memory. Incertain examples, a non-transitory storage medium may store data thatcan, over time, change (e.g., in Random Access Memory (RAM) or cache).

Although the FIG. 2 shows exemplary units of the source UE102 but it isto be understood that other embodiments are not limited thereon. Inother embodiments, the source UE102 may include less or more number ofunits. Further, the labels or names of the units are used only forillustrative purpose and does not limit the scope of the invention. Oneor more units can be combined together to perform same or substantiallysimilar function to generate and transmit the unicast parameter and thegroupcast parameter from the source UE 102.

FIG. 3 illustrates various units of the destination UE 104, according toan embodiment as disclosed herein. In an embodiment, the destination UE104 includes a communication unit 302, a processor unit 304, and astorage unit 306. The operation and functionality of the destination UE104 is similar to the source UE 102. In an embodiment, the communicationunit 302 is configured to receive the D2D MAC PDU. After receiving theD2D MAC PDU, the processor unit 304 is configured to detect whether theD2D MAC PDU includes one of the unicast parameters and the groupcastparameters. In response to detection, the processor unit 304 isconfigured to identify the D2D MAC PDU corresponding to the unicast D2Dcommunication when the unicast parameters are detected. In response todetection, the processor unit 304 is configured to identify the D2D MACPDU corresponding to the groupcast D2D communication when the groupcastparameters are detected.

In an embodiment, the unicast parameter can be, for example but notlimited to, a unicast D2D MAC PDU format version number, a unicastpacket indicator, a scrambled Cyclic Redundancy Check (CRC) of aScheduling Assignment (SA), a number of bits, values, size associatedwith at least one of an identifier of the source UE 102, a groupidentifier of the source UE 102, an identifier of the destination UE 104or the like.

In an embodiment, the D2D MAC PDU, for the unicast D2D communication,includes the unicast D2D MAC PDU format version, reserved bits, theidentifier of the source UE 102, a unicast identifier of the destinationUE 102, MAC sub-headers, and a unicast MAC Service Data Unit (SDU).

In an embodiment, the D2D MAC PDU, for the unicast D2D communication,includes the unicast D2D MAC PDU format version, reserved bits having aunicast Packet Indicator (UPI), an identifier of the source UE 102, theunicast identifier of the destination UE 104, the MAC sub-headers, andthe unicast MAC SDU.

In an embodiment, the D2D MAC PDU, for the unicast D2D communicationacross groups, includes at least one of the unicast D2D MAC PDU formatversion, the reserved bits, the identifier of the source UE 102, thegroup identifier of the source UE 102, the unicast identifier of thedestination UE 104, the group identifier of the destination UE 104, theMAC sub-headers, and the unicast MAC SDU.

In an embodiment, the D2D MAC PDU, for the unicast D2D communicationwithin a group, includes at least one of a unicast D2D MAC PDU formatversion, the reserved bits, the identifier of the source UE 102, theunicast identifier of the destination UE 104, the group identifier ofthe destination UE 104, the MAC sub-headers, and the unicast MAC SDU.

In an embodiment, the D2D MAC PDU, for the unicast D2D communication forone of within the group and across the groups, includes at least one ofthe unicast D2D MAC PDU format version, the reserved bits including thegroup identifier, the identifier of the source UE 102, the unicastidentifier of the destination UE 104, the group identifier of thedestination UE 104, the MAC sub-headers, and the unicast MAC SDU.

In an embodiment, the processor unit 304 is configured to identify theD2D MAC PDU corresponding to the groupcast D2D communication when thegroupcast parameters are detected.

In an embodiment, the groupcast parameter can be, for example but notlimited to, a groupcast D2D MAC PDU format version, an unscrambled CRCof the SA, the number of bits, values, size associated with at least oneof an identifier of the source UE 102, a group identifier of the sourceUE 102, an identifier of the destination UE 104 or the like.

In an embodiment, the D2D MAC PDU, for the groupcast D2D communication,includes at least one of a groupcast D2D MAC PDU format version, thereserved bits, the identifier of the source UE 102, the group identifierof the source UE 102, the identifier of the destination UE 104, agroupcast identifier of the destination UE 104, the MAC sub-headers, anda groupcast MAC SDU.

Although the FIG. 3 shows exemplary units of the destination UE104 butit is to be understood that other embodiments are not limited thereon.In other embodiments, the destination UE104 may include less or morenumber of units. Further, the labels or names of the units are used onlyfor illustrative purpose and does not limit the scope of the invention.One or more units can be combined together to perform same orsubstantially similar function to discriminate between the unicast D2Dcommunication and the groupcast D2D communication at the destination UE104.

FIG. 4a is a flow diagram illustrating a method 400 a for generating andtransmitting the D2D MAC PDU at the source UE 102, according to anembodiment as disclosed herein. At step 402 a, the method 400 a includesgenerating the D2D MAC PDU including one of unicast parameters and thegroupcast parameters. In an embodiment, the method 400 allows theprocessor unit 204 to generate the D2D MAC PDU including one of unicastparameters and the groupcast parameters. At step 404 a, the method 400 aincludes sending the D2D MAC PDU to the destination (i.e. destination UE104 in case of unicast D2D communication or destination group in case ofgroupcast D2D communication). In an embodiment, the method 400 a allowsthe communication unit 202 to transmit the D2D MAC PDU to thedestination (i.e. destination UE 104 in case of unicast D2Dcommunication or destination group in case of groupcast D2Dcommunication).

In an example, the MAC PDU format version number field indicates whichversion of a Sidelink Shared Channel (SL-SCH) subheader is used. In thisversion of the specification two format versions are defined, and thisfield shall therefore be set to “0001” or “0010”. The V field size is 4bits. SRC: The Source Layer-2 ID field carries the identity of thesource. It is set to the ProSe UE ID. The SRC field size is 24 bits. Ifthe V field is set to “0001” this identifier is the groupcastidentifier. If the V field is set to “0010” this identifier is a unicastidentifier. DST: The DST field carries the 16 most significant bits ofthe Destination Layer-2 ID. The Destination Layer-2 ID is set to theProSe Layer-2 Group ID or ProSe UE ID. If the V field is set to “0001”this identifier is the groupcast identifier. If the V field is set to“0010” this identifier is the unicast identifier.

The various actions, acts, blocks, steps, or the like in the method 400a may be performed in the order presented, in a different order orsimultaneously. Further, in some embodiments, some of the actions, acts,blocks, steps, or the like may be omitted, added, modified, skipped, orthe like without departing from the scope of the invention.

FIG. 4b is a flow diagram illustrating a method 400 b for discriminatingbetween the unicast D2D communication and the groupcast D2Dcommunication at the destination UE 104, according to an embodiment asdisclosed herein. At step 402 b, the method 400 b includes receiving theD2D MAC PDU. In an embodiment, the method 400 b allows the communicationunit 302 to receive the D2D MAC PDU. At step 404 b, the method 400 bincludes detecting whether D2D MAC PDU includes one of unicastparameters and groupcast parameters. In an embodiment, the method 400 ballows the processor unit 304 to detect whether D2D MAC PDU includes oneof unicast parameters and groupcast parameters. At step 406 b, themethod 400 b includes identifying that the D2D MAC PDU is one of theunicast D2D communication when the unicast parameters are detected. Inan embodiment, the method 400 b allows the processor unit 304 toidentify that the D2D MAC PDU is one of the unicast D2D communicationwhen the unicast parameters are detected. At step 408 b, the method 400b includes identifying that the D2D MAC PDU is one of the groupcast D2Dcommunication when the groupcast parameters are detected. In anembodiment, the method 400 b allows the processor unit 304 to identifythat the D2D MAC PDU is one of the groupcast D2D communication when thegroupcast parameters are detected.

The various actions, acts, blocks, steps, or the like in the method 400b may be performed in the order presented, in a different order orsimultaneously. Further, in some embodiments, some of the actions, acts,blocks, steps, or the like may be omitted, added, modified, skipped, orthe like without departing from the scope of the invention.

FIG. 5a is a flow diagram illustrating source UE operations for the D2DMAC PDU generation and transmission which includes one of unicastparameters and groupcast parameters, according to an embodiment asdisclosed herein. At 502, the source UE 102 is configured to determinewhether the MAC SDU(s) to be transmitted in D2D MAC PDU is for theunicast D2D communication or the groupcast D2D communication. If the MACSDU(s) to be transmitted in D2D MAC PDU is for the unicast D2Dcommunication, at 504 a, the source UE 102 is configured to transmit theSA. In an embodiment, the L1 ID in the SA/SC is set to 8 LSBs of D2D UEID of the destination UE 104. At 506 a, the source UE 102 is configuredto set the D2D MAC PDU format version field to ‘X’ in the MAC header ofthe D2D MAC PDU. In an example, the 4 bits D2D MAC PDU format versionnumber field is set to ‘0010’ (i.e. decimal value 2) in the MAC headerof the D2D MAC PDU.

At 508 a, the source UE 102 is configured to set the DST field in theMAC header of the D2D MAC PDU to 16 MSBs of the D2D UE ID of thedestination UE 104. Alternatively, at 508 a, the source UE 102 isconfigured to set the DST field in the MAC header of the D2D MAC PDU to24 MSBs of D2D UE ID of the destination UE 104. The D2D UE ID set in DSTfield is the unicast identifier of destination UE. At 510 a, the sourceUE 102 is configured to set 24 bit SRC field in the MAC header of theD2D MAC PDU to the D2D UE ID of the source UE 102 wherein the length ofD2D UE ID of source UE 102 is 24 bits. Alternatively, at 510 a, thesource UE 102 is configured to set 32 bit SRC field in the MAC header ofthe D2D MAC PDU to the D2D UE ID of the source UE 102 wherein the lengthof D2D UE ID of source UE 102 is 32 bits. The D2D UE ID set in SRC fieldis the unicast identifier of the source UE 102 and identifies the sourceUE 102. At 512 a, the source UE 102 is configured to include the MACsub-header(s) in the MAC header corresponding to MAC SDU(s) in the D2DMAC PDU payload. At 514 a, the source UE 102 is configured to transmitthe D2D MAC PDU.

If the MAC SDU(s) to be transmitted in D2D MAC PDU is for the groupcastD2D communication, at 504 b, the source UE 102 is configured to transmitthe SA. The L1 ID field in the SA/SC is set to 8 LSBs of the D2D layer-2group ID of the destination group. At 506 b, the source UE 102 isconfigured set the D2D MAC PDU format version number field to ‘Y’ in theMAC header. In an example, the 4 bits D2D MAC PDU format version numberis set to 0001 (i.e., decimal value 1) in the MAC header of the D2D MACPDU. At 508 b, the source UE 102 is configured set the DST field in theMAC header to 16 MSBs of D2D Layer-2 Group ID of the destination group.At 510 b, the source UE 102 is configured set the 24 bit SRC field inthe MAC header to the D2D UE ID of the source UE 102. At 512 b, thesource UE 102 is configured to include the MAC sub-header(s) in the MACheader corresponding to the MAC SDU(s) in the D2D MAC PDU payload. At514 b, the source UE 102 is configured transmit the D2D MAC PDU.

The various actions, acts, blocks, steps, or the like in the source UEoperations may be performed in the order presented, in a different orderor simultaneously. Further, in some embodiments, some of the actions,acts, blocks, steps, or the like may be omitted, added, modified,skipped, or the like without departing from the scope of the invention.

FIG. 5b to FIG. 5d illustrates an example of the D2D MAC PDU format asdescribed in the FIG. 5a , according to an embodiment as disclosedherein. Consider, the source UE 102 is assigned separate D2D UE ID forthe unicast D2D communication and the groupcast D2D communication. Thevalues for the D2D UE ID and D2D Layer 2 Group ID are 24 bits values andassigned from same address space independently. There is no partition ofaddress space between the unicast ID (i.e. D2D UE ID) and the group ID(i.e. D2D Layer 2 group ID). In an embodiment, the D2D UE ID for theunicast D2D communication is assigned by a D2D server. The D2D UE ID andthe D2D Layer 2 group ID for the group communication are assigned by aD2D key management function.

In an embodiment, the D2D UE ID for the unicast D2D communication isselected by the source UE itself. The D2D UE ID and the D2D Layer 2group ID for the group communication are assigned by the D2D keymanagement function.

In an embodiment, the D2D MAC PDU format version number in the MACheader is used to distinguish between the D2D MAC PDU carrying theunicast and groupcast MAC SDUs. Whether the D2D MAC PDU carries unicastor groupcast MAC SDUs is indicated using distinct values of D2D MAC PDUformat version number. The SRC/DST fields of the MAC header are set tounicast or groupcast IDs according to the D2D MAC PDU format versionnumber.

In an embodiment, the MAC layer protocol in a communication unit 202first determines whether the MAC SDU(s) to be transmitted in the D2D MACPDU is for the unicast D2D communication or the groupcast D2Dcommunication. The MAC layer protocol receives information from upperlayers (e.g. Radio Link Control (RLC) layer) along with the MAC SDU(i.e., RLC PDU) indicating whether the MAC SDU is for the unicast D2Dcommunication or the groupcast D2D communication. If the MAC SDU(s) isfor the unicast D2D communication then, the MAC layer generates the D2DMAC PDU as follows.

The 4 bits D2D MAC PDU format version number is included in the MACheader and is set to ‘X’ (e.g. 0010 in binary or 2 in decimal) in theMAC header of the D2D MAC PDU. Note that the D2D MAC PDU format versionnumber in the MAC header is distinct for the unicast D2D MAC PDU and thegroupcast D2D MAC PDU. In an embodiment, if the scrambled CRC is usedfor the SA information corresponding to the unicast D2D MAC PDU then 4bits of the D2D MAC PDU format version number may be set same for bothunicast and groupcast D2D MAC PDU.

The 4 reserved bits following the D2D MAC PDU format version number isset to zeros.

The 24 bits SRC field is included in the MAC header. In an embodiment,the 24 bits SRC field in the MAC header of D2D MAC PDU is set to the D2DUE ID of the source UE 102 where the length of D2D UE ID of the sourceUE is 24 bits as shown in the FIG. 5c . In an embodiment, 32 bits SRCfield is included in the MAC header as shown in the FIG. 5d . The 32bits SRC field in the MAC header of the D2D MAC PDU is set to the D2D UEID of the source UE 102, where the length of the D2D UE ID of the sourceUE 102 is 32 bits. The D2D UE ID encoded in the SRC field is the unicastidentifier of the source UE 102 and identifies the source UE 102.

The 16 bit DST field is also included in the MAC header as shown in theFIG. 5c . In an embodiment, the 16 bits DST field in the MAC header ofD2D MAC PDU is set to 16 MSBs of the D2D UE ID of the destination UE104. In an embodiment, 24 bit DST field is included in the MAC header asshown in the FIG. 5d . The 24 bits DST field in the MAC header of D2DMAC PDU is set to 24 MSBs of D2D UE ID of the destination UE 104. TheD2D UE ID encoded in the DST field is the unicast identifier of thedestination UE 104.

The MAC subheader(s) in the MAC header corresponding to the MAC SDU(s)and/or padding is then included in the D2D MAC PDU payload.

The SA or scheduling control (SC) including the L1 ID field set to 8LSBs of destination ProSe UE ID and CRC bits is transmitted prior totransmission of unicast D2D MAC PDU.

In an embodiment, the SA or SC including the L1 ID field set to 8 LSBsof destination D2D UE ID and with scrambled CRC bits is transmittedprior to transmission of the D2D MAC PDU. The SA is protected using theCRC. The SA information is used to calculate a set of CRC parity bits.The scheduling information bits are divided by a CRC generatorpolynomial to generate 16 CRC parity bits. The CRC parity bits are thenscrambled using a pre-defined CRC mask. The scrambled CRC is obtained byperforming a bit-wise XOR operation of the 16 bit calculated CRC paritybits and bits of pre-defined CRC mask.

The proposed technique indicates whether the D2D MAC PDU carries theunicast or groupcast MAC SDUs using distinct values of the D2D MAC PDUformat version number. The proposed technique can be used to encode ordecode the different values and sizes in the SRC/DST fields of the MACHeader depending on whether the D2D MAC PDU carries unicast or groupcastMAC SDUs. The proposed technique indicates whether the D2D MAC PDUcarries the unicast or groupcast MAC SDUs using the scrambled andunscrambled CRC of the SA (i.e., scrambled CRC using a predefined CRCmask for the SA corresponding to the unicast D2D MAC PDU and unscrambledCRC for the SA corresponding to a non-unicast D2D MAC PDU).

FIG. 5e is a flow diagram illustrating destination UE operations fordiscriminating between the unicast D2D communication and the groupcastD2D communication based on the D2D MAC PDU format version number,according to an embodiment as disclosed herein. At 502 e, thedestination UE 104 is configured to receive the SA/SC and D2D MAC PDU.At 504 e, the destination UE 104 is configured to determine whether theD2D MAC PDU is for the unicast D2D communication or groupcast D2Dcommunication based on the D2D MAC PDU format version number in the MACheader of D2D MAC PDU.

If the D2D MAC PDU is for the unicast D2D communication, at 506 e, thedestination UE 104 is configured to identify the source UE ID using theSRC field in the MAC header and the destination UE ID using the DSTfield in the MAC header and L1 ID field in the SA/SC. If the D2D MAC PDUis for the groupcast D2D communication, at 508 e, the destination UE 104is configured to identify the source UE ID using the SRC field in theMAC header and the destination Group ID using the DST field in the MACheader and L1 ID field in SA/SC.

The various actions, acts, blocks, steps, or the like in the destinationUE operation may be performed in the order presented, in a differentorder or simultaneously. Further, in some embodiments, some of theactions, acts, blocks, steps, or the like may be omitted, added,modified, skipped, or the like without departing from the scope of theinvention.

FIG. 5f is a flow diagram illustrating destination UE operations fordiscriminating between the unicast D2D communication and the groupcastD2D communication based on the CRC of SA/SC, according to an embodimentas disclosed herein. At 502 f, the destination UE 104 is configured toreceive the SA/SC and D2D MAC PDU. At 504 f, the destination UE 104 isconfigured to determine whether the D2D MAC PDU is for the unicast D2Dcommunication or groupcast D2D communication based on the CRC of SA/SC.If the CRC is scrambled using the pre-defined CRC mask then D2D MAC PDUis for the unicast D2D communication otherwise D2D MAC PDU is for thegroupcast D2D communication.

If the D2D MAC PDU is for the unicast D2D communication, at 506 f, thedestination UE 104 is configured to identify the source UE ID using theSRC field in the MAC header and the destination UE ID using the DSTfield in the MAC header and L1 ID field in the SA/SC. If the D2D MAC PDUis for the groupcast D2D communication, at 508 f, the destination UE 104is configured to identify the source UE ID using the SRC field in theMAC header and the destination Group ID using the DST field in the MACheader and L1 ID field in SA/SC.

The various actions, acts, blocks, steps, or the like in the destinationUE operation may be performed in the order presented, in a differentorder or simultaneously. Further, in some embodiments, some of theactions, acts, blocks, steps, or the like may be omitted, added,modified, skipped, or the like without departing from the scope of theinvention.

FIG. 6a is a flow diagram illustrating source UE operations for D2D MACPDU generation and transmission which includes the unicast PacketIndicator (UPI), according to an embodiment as disclosed herein. At 602,the source UE 102 is configured to determine whether the D2D MAC PDU isfor the unicast D2D communication or the groupcast D2D communication. Ifthe D2D MAC PDU is for the unicast D2D communication, at 604 a, thesource UE 102 is configured to transmit the SA. In an embodiment, the L1ID in the SA/SC is set to 8 LSBs of D2D UE ID of the destination UE 104.At 606 a, the source UE 102 is configured to set the D2D MAC PDU formatversion number field to ‘X’ in the MAC header of the D2D MAC PDU. In anexample, the 4 bits D2D MAC PDU format version number is set to 0010(i.e., decimal value 2) in the MAC header of the D2D MAC PDU. At 608 a,the source UE 102 is configured to set the DST field in the MAC headerof the D2D MAC PDU to 16 MSBs of the D2D UE ID of the destination UE104. Alternatively, at 608 a, the source UE 102 is configured to set theDST field in the MAC header of the D2D MAC PDU to 24 MSBs of D2D UE IDof the destination UE 104.

At 610 a, the source UE 102 is configured to set 24 bit SRC field in theMAC header of the D2D MAC PDU to the D2D UE ID of the source UE 102wherein the length of D2D UE ID of source UE 102 is 24 bits.Alternatively, at 610 a, the source UE 102 is configured to set 32 bitSRC field in the MAC header of the D2D MAC PDU to the D2D UE ID of thesource UE 102 wherein the length of D2D UE ID of source UE 102 is 32bits. At 612 a, the source UE 102 is configured to include the UPI fieldin the MAC header of the D2D MAC PDU and set the UPI field to one. At614 a, the source UE 102 is configured to set the MAC sub-header(s) inthe MAC header corresponding to the MAC SDU(s) in the D2D MAC PDUpayload. At 616 a, the source UE 102 is configured to transmit the D2DMAC PDU.

If the D2D MAC PDU is for the groupcast D2D communication, at 604 b, thesource UE 102 is configured to transmit the SA. The L1 ID field in theSA/SC is set to 8 LSBs of the D2D layer-2 group ID of the destinationgroup. At 606 b, the source UE 102 is configured to set the D2D MAC PDUformat version number to ‘Y’ in the MAC header. In an example, the 4bits D2D MAC PDU format version number is set to 0001 (i.e., decimalvalue 1) in the MAC header of the D2D MAC PDU. At 608 b, the source UE102 is configured to set the DST field in the MAC header to 16 MSBs ofD2D Laye-2 Group ID of the destination UE 104. At 610 b, the source UE102 is configured to set the 24 bit SRC field in the MAC header to theD2D UE ID of the source UE 102. At 612 b, the source UE 102 isconfigured to provide the MAC sub-header(s) in the MAC headercorresponding to the MAC SDU(s) in the D2D MAC PDU payload. At 614 b,the source UE 102 is configured to transmit the D2D MAC PDU.

The various actions, acts, blocks, steps, or the like in the source UEoperations may be performed in the order presented, in a different orderor simultaneously. Further, in some embodiments, some of the actions,acts, blocks, steps, or the like may be omitted, added, modified,skipped, or the like without departing from the scope of the invention.

FIG. 6b to FIG. 6d illustrates an example of the D2D MAC PDU format asdescribed in the FIG. 6a , according to an embodiment as disclosedherein. Consider, the MAC layer protocol in the transmitter unit 202first determines whether the MAC SDU(s) to be transmitted in the D2D MACPDU is for the unicast D2D communication or the groupcast D2Dcommunication. The MAC layer protocol receives information from theupper layers (e.g. RLC layer) along with the MAC SDU (i.e. RLC PDU)indicating whether the MAC SDU is for the unicast D2D communication orthe groupcast D2D communication. If the MAC SDU(s) is for the unicastD2D communication, then the MAC layer generates the D2D MAC PDU asfollows.

The 4 bits D2D MAC PDU format version number is included in the MACheader and is set to ‘X’ (e.g. 0010 in binary or 2 in decimal) in theMAC header of the D2D MAC PDU. Note that the D2D MAC PDU format versionnumber in the MAC header is distinct for the unicast D2D MAC PDU and thegroupcast D2D MAC PDU. In an embodiment, if the scrambled CRC is usedfor the SA information corresponding to the unicast D2D MAC PDU then the4 bits of the D2D MAC PDU format version number may be set same for bothunicast and groupcast D2D MAC PDU.

The 3 reserved bits following the D2D MAC PDU format version number isset to zeros.

The UPI field is included in the MAC header and is set to ‘1’ as shownin the FIG. 6c and FIG. 6d .

The 24 bits SRC field is included in the MAC header as shown in the FIG.6c . The 24 bits SRC field in the MAC header of the D2D MAC PDU is setto D2D UE ID of the source UE 102, where the length of D2D UE ID of thesource UE is 24 bits. In an embodiment, 32 bits SRC field is included inthe MAC header as shown in the FIG. 6d . The 32 bits SRC field in theMAC header of the D2D MAC PDU is set to D2D UE ID of the source UE 102,where the length of D2D UE ID of the source UE 102 is 32 bits. The D2DUE ID encoded in the SRC field is the unicast identifier of the sourceUE 102 and identifies the source UE.

The 16 bit DST field is also included in the MAC header as shown in theFIG. 6c . The 16 bits DST field in the MAC header of the D2D MAC PDU isset to 16 MSBs of the D2D UE ID of the destination UE 104. In anembodiment, 24 bit DST field is included in the MAC header as shown inthe FIG. 6d . The 24 bits DST field in the MAC header of the D2D MAC PDUis set to 24 MSBs of D2D UE ID of the destination UE 104. The D2D UE IDencoded in the DST field is the unicast identifier of the destinationUE.

The MAC subheader(s) in the MAC header corresponding to MAC SDU(s)and/or padding is then included in the D2D MAC PDU payload.

The SA or SC including the L1 ID field set to 8 LSBs of Destination D2DUE ID and CRC bits are transmitted prior to transmission of the D2D MACPDU.

In an embodiment, the SA or the SC including the L1 ID field set to 8LSBs of destination D2D UE ID and with scrambled CRC bits is transmittedprior to transmission of the D2D MAC PDU. The SA is protected using theCRC. The SA information is used to calculate the set of CRC parity bits.The scheduling information bits are divided by the CRC generatorpolynomial to generate 16 CRC parity bits. The CRC parity bits are thenscrambled using the pre-defined CRC mask. The scrambled CRC is obtainedby performing a bit-wise XOR operation of the 16 bit calculated CRCparity bits and bits of pre-defined CRC mask.

The proposed technique can be used to indicate whether the D2D MAC PDUcarries the unicast MAC SDUs using D2D MAC PDU format version number andUPI. The proposed technique can be used to indicate whether the D2D MACPDU carries the unicast MAC SDUs using the unicast packet indicator andthe scrambled CRC of the SA information (i.e., scrambled CRC usingpredefined CRC mask for the SA corresponding to the unicast D2D MAC PDUand the unscrambled CRC for the SA corresponding to the non-unicast D2DMAC PDU.

The proposed technique can be used to determine the presence of theunicast packet indicator field in the MAC header using the D2D MAC PDUformat version number or the scrambled CRC of the SA. The proposedtechnique can be used to encode/decode the different values and sizes inthe SRC/DST fields of the MAC header depending on whether the D2D MACPDU carries unicast or groupcast MAC SDUs.

FIG. 6e is a flow diagram illustrating destination UE operations whilediscriminating the unicast D2D communication and the groupcast D2Dcommunication using the UPI, according to an embodiment as disclosedherein. At 602 e, the destination UE 104 is configured to receive theD2D MAC PDU. At 604 e, the destination UE 104 is configured to detectwhether the D2D MAC PDU includes the unicast parameters or the groupcastparameters. If the D2D MAC PDU includes the groupcast parameters, at 606e, the destination UE 104 is configured to read the SRC and DST fieldsin MAC header and identify the source UE ID using the SRC field in theMAC header and Destination Group ID using the DST field in MAC headerand L1 ID field in SA/SC.

If the D2D MAC PDU corresponds to the unicast parameters, at 608 e, thedestination UE 104 is configured to determine whether the unicast packetindicator field corresponding to “zero” or “one”. If the unicast packetindicator field corresponds to “one”, at 610 e, the destination UE 104is configured to read the SRC and DST fields in MAC header and identifythe source UE ID using the SRC field in the MAC header and DestinationUE ID using the DST field in MAC header and L1 ID field in SA/SC. If theunicast packet indicator field corresponds to “zero”, at 612 e, thedestination UE 104 is configured to indicate an error signal or performthe operation same manner as if the D2D MAC PDU format version number is‘0001’ (i.e. decimal value 1).

The various actions, acts, blocks, steps, or the like in the receivingunit operation may be performed in the order presented, in a differentorder or simultaneously. Further, in some embodiments, some of theactions, acts, blocks, steps, or the like may be omitted, added,modified, skipped, or the like without departing from the scope of theinvention.

FIGS. 7a and 7b illustrates an example of the D2D MAC PDU format forunicast across groups, according to an embodiment as disclosed herein.Consider, the unicast D2D communication is established within themembers of the group or within members of different groups. The MAClayer protocol in the communication unit 202 first determines whetherthe MAC SDU(s) to be transmitted in the D2D MAC PDU is for the unicastD2D communication or the groupcast D2D communication. The MAC layerprotocol receives information from the upper layers (e.g. RLC layer)along with the MAC SDU (i.e. RLC PDU) indicating whether the MAC SDU isfor the unicast D2D communication or the groupcast D2D communication. Ifthe MAC SDU(s) is for the unicast D2D communication then, the MAC layergenerates the D2D MAC PDU as follows.

The 4 bits D2D MAC PDU format version number is included in the MACheader and is set to ‘X’ (e.g. 0010 in binary or 2 in decimalrepresentation) in the MAC header of the D2D MAC PDU. Note that the D2DMAC PDU format version number in the MAC header is distinct for theunicast D2D MAC PDU and the groupcast D2D MAC PDU. In an embodiment, ifthe scrambled CRC is used for the SA information corresponding to theunicast D2D MAC PDU then, 4 bits of D2D MAC PDU format version numbermay be set same for both unicast and groupcast D2D MAC PDU.

The 4 reserved bits following the D2D MAC PDU format version number isset to zeros.

The 24 bits SRC field is included in the MAC header. The 24 bits SRCfield in the MAC header of the D2D MAC PDU is set to D2D UE ID of thesource UE 102. The D2D UE ID encoded in the SRC field is the unicastidentifier of the source UE 102.

The 24 bits SRC GRP ID field is included in the MAC header. The 24 bitsSRC GRP ID field in the MAC header of the D2D MAC PDU is set to D2DLayer-2 Group ID of the source UE 102.

The 24 bits DST UE ID field is included in the MAC header. The 24 bitsDST UE ID field in the MAC header of the D2D MAC PDU is set to the D2DUE ID of the destination UE. The D2D UE ID encoded in the DST UE fieldis the unicast address of the destination UE 104 of the group identifiedby D2D Layer-2 Group ID encoded in the DST field in the MAC header andthe SA.

The 16 bit DST field is also included in the MAC header. The 16 bits DSTfield in the MAC header of the D2D MAC PDU is set to 16 MSBs of D2DLayer-2 group ID of the destination UE 104.

The MAC subheader(s) in the MAC header corresponding to MAC SDU(s)and/or padding is then included in the D2D MAC PDU payload.

In an embodiment, the SRC GRP ID and the DST UE ID are included in theMAC Control Element (CE) instead of the MAC header as shown in the FIG.7b .

In an embodiment, the SA including the 8 LSBs of destination UE's D2DLayer-2 Group ID and the CRC bits is transmitted prior to transmissionof the D2D MAC PDU. In an embodiment, the SA including the 8 LSBs ofdestination UE's D2D Layer-2 Group ID and with scrambled CRC bits istransmitted prior to transmission of the D2D MAC PDU. The SA isprotected using the CRC. The SA information is used to calculate a setof CRC parity bits. The scheduling information bits are divided by theCRC generator polynomial to generate 16 CRC parity bits. The CRC paritybits are then scrambled using the pre-defined CRC mask. The scrambledCRC is obtained by performing the bit-wise XOR operation of the 16 bitcalculated CRC parity bits and bits of pre-defined CRC mask.

In an embodiment, the full destination UE's group ID is included in theMAC header, 16 MSBs of DST UE ID is included in the MAC header, and 8LSBs of DST UE ID is included in the SA information.

The proposed technique can be used to indicate whether the D2D MAC PDUcarries the unicast MAC SDUs or the groupcast MAC SDUs using the D2D MACPDU format version number or scrambled CRC of the SA (i.e., scrambledCRC using the predefined CRC mask for the SA corresponding to theunicast D2D MAC PDU and unscrambled CRC for the SA corresponding to thenon-unicast D2D MAC PDU. The proposed technique can be used to encode/decode the SRC/SRC GRP ID/DST UE ID/DST fields in case of unicast D2DMAC PDU and encode/decode the SRC/DST fields in case of non-unicast D2DMAC PDU.

FIGS. 8a and 8b illustrates an example of the D2D MAC PDU format forunicast within groups, according to an embodiment as disclosed herein.Consider, the unicast D2D communication is established only within themembers of a group. The MAC layer protocol in the communication unit 202first determines whether the MAC SDU(s) to be transmitted in the D2D MACPDU is for the unicast D2D communication or not. The MAC layer protocolreceives information from the upper layers (e.g. RLC) along with the MACSDU (i.e. RLC PDU) indicating whether the MAC SDU is for the unicast D2Dcommunication or not. If the MAC SDU(s) is for unicast then MAC layergenerates the D2D MAC PDU as follows.

The 4 bits D2D MAC PDU format version number is included in the MACheader and is set to ‘X’ (e.g. 0010 in binary or 2 in decimal) in theMAC header of the D2D MAC PDU. Note that, the D2D MAC PDU format versionnumber in the MAC header is distinct for the unicast D2D MAC PDU and thenon-unicast D2D MAC PDU. In an embodiment, if the scrambled CRC is usedfor the SA information corresponding to the unicast D2D MAC PDU then, 4bits of D2D MAC PDU format version number may be set same for bothunicast D2D MAC PDU and non-unicast D2D MAC PDU.

The 4 reserved bits following the D2D MAC PDU format number is set tozeros.

The 24 bits SRC field is included in the MAC header. The 24 bits SRCfield in the MAC header of the D2D MAC PDU is set to D2D UE ID of thesource UE 102. The D2D UE ID encoded in the SRC field is the unicastaddress of the source UE 102 and is unique within the group.

The 24 bits DST UE ID field is included in the MAC header. The 24 bitsDST UE ID field in the MAC header of the D2D MAC PDU is set to the D2DUE ID of the destination UE 104. The D2D UE ID encoded in the DST UEfield is the unicast address of the destination UE 104 of the groupidentified by the D2D Layer-2 Group ID encoded in the DST field in theMAC header and the SA.

The 16 bit DST field is also included in the MAC header. The 16 bits DSTfield in MAC header of D2D MAC PDU is set to 16 MSBs of D2D Layer-2Group ID of the destination UE. This field identifies both source UE andDestination UE's group.

The MAC subheader(s) in the MAC header corresponding to MAC SDU(s)and/or padding is then included in the D2D MAC PDU payload.

In an embodiment, the DST UE ID can be included in MAC Control Elementinstead of MAC header as illustrated in the FIG. 8b .

The scheduling assignment including the 8 LSBs of source/destinationUE's D2D Layer-2 group ID and the CRC bits is transmitted prior totransmission of the D2D MAC PDU. In an embodiment, the SA including the8 LSBs of source/destination UE's D2D Layer-2 group ID and withscrambled CRC bits is transmitted prior to transmission of the D2D MACPDU. The SA is protected using the CRC. The SA information is used tocalculate the set of CRC parity bits. The scheduling information bitsare divided by the CRC generator polynomial to generate 16 CRC paritybits. The CRC parity bits are then scrambled using the pre-defined CRCmask. The scrambled CRC is obtained by performing the bit-wise XORoperation of the 16 bit calculated CRC parity bits and bits ofpre-defined CRC mask.

In an embodiment, the destination UE's group ID may be included in theMAC header and 16 MSBs of DST UE ID is included in the MAC header and 8LSBs of DST UE ID is included in the SA information.

The proposed technique can be used to indicate whether the D2D MAC PDUcarries the unicast MAC SDUs or groupcast MAC SDUs using the D2D MAC PDUformat version number or scrambled CRC of scheduling assignment (i.e.,scrambled CRC using the predefined CRC mask for the SA corresponding tothe unicast D2D MAC PDU and unscrambled CRC for the SA corresponding tothe non-unicast D2D MAC PDU.

The proposed method can be used to encode /decode the SRC/DST UE ID/DSTfields in case of the unicast D2D MAC PDU and encode/decode the SRC/DSTfields in case of non-unicast D2D MAC PDU.

FIGS. 9a and 9b illustrate an example of the D2D MAC PDU format forunicast within group or across groups, according to an embodiment asdisclosed herein. Consider the unicast D2D communication is establishedwithin the members of a group or across groups. The MAC layer protocolin the communication unit 202 first determines whether the MAC SDU(s) tobe transmitted in the D2D MAC PDU is for the unicast D2D communicationor not. The MAC layer protocol receives information from the upperlayers (e.g. RLC layer) along with the MAC SDU (i.e. RLC PDU) indicatingwhether the MAC SDU is for the unicast D2D communication or not. If theMAC SDU(s) is for unicast then MAC layer generates the D2D MAC PDU asfollows.

The 4 bits D2D MAC PDU format version number is included in MAC headerand is set to ‘X’ (e.g. 0010 in binary or 2 in decimal) in the MACheader of the D2D MAC PDU. Note that D2D MAC PDU format version numberin the MAC header is distinct for the unicast D2D MAC PDU and thenon-unicast D2D MAC PDU. In an embodiment, if the scrambled CRC is usedfor the SA information corresponding to the unicast D2D MAC PDU then 4bits of D2D MAC PDU format version number may be set same for bothunicast and non-unicast D2D MAC PDU.

The 3 reserved bits following the D2D MAC PDU format version number isset to zeros.

The group indicator field is also included in the MAC header. Itindicates whether destination UE is within same group as the source UE102 or not. In an embodiment, the distinct D2D MAC PDU format versionnumber can indicate whether destination UE is within same group assource UE or not.

The 24 bits SRC field is included in the MAC header. The 24 bits SRCfield in the MAC header of the D2D MAC PDU is set to the D2D UE ID ofthe source UE 102. The D2D UE ID encoded in the SRC field is the unicastaddress of the source UE and is unique within the group.

The 24 bits SRC GRP ID field is included in the MAC header if group ofsource UE 102 and destination UE 104 is different. The 24 bits SRC GRPID field in the MAC header of the D2D MAC PDU is set to D2D Layer-2group ID of the source UE 102.

The 24 bits DST UE ID field is included in the MAC header. The 24 bitsDST UE ID field in the MAC header of the D2D MAC PDU is set to the D2DUE ID of the destination UE 104. The D2D UE ID encoded in the DST UEfield is the unicast address of the destination UE of the groupidentified by the D2D Layer-2 Group ID encoded in the DST field in theMAC header and the SA.

The 16 bit DST field is also included in the MAC header. The 16 bits DSTfield in the MAC header of the D2D MAC PDU is set to 16 MSBs of ProSeLayer-2 Group ID of the destination UE.

The MAC subheader(s) in the MAC header corresponding to the MAC SDU(s)and/or padding is then included in the D2D MAC PDU payload.

In an embodiment, the GI/DST UE ID/SRC GRP ID are included in the MACControl Element instead of the MAC header as illustrated in the FIG. 9b.

In an embodiment, the destination UE's group ID may be included in theMAC header, 16 MSBs of DST UE ID is included in the MAC header, and 8LSBs of DST UE ID is included in the SA information.

The SA including the 8 LSBs of destination UE's D2D Layer-2 Group ID andCRC bits is transmitted prior to transmission of D2D MAC PDU. In anembodiment, the SA including the 8 LSBs of destination UE's D2D Layer-2Group ID and with scrambled CRC bits is transmitted prior totransmission of the D2D MAC PDU. The SA is protected using the CRC. TheSA information is used to calculate the set of CRC parity bits. Thescheduling information bits are divided by the CRC generator polynomialto generate 16 CRC parity bits. The CRC parity bits are then scrambledusing the pre-defined CRC mask. The scrambled CRC is obtained byperforming the bit-wise XOR operation of the 16 bit calculated CRCparity bits and bits of pre-defined CRC mask.

The proposed technique can be used to indicate whether the D2D MAC PDUcarries the unicast MAC SDUs or the groupcast MAC SDUs using the D2D MACPDU format version number or scrambled CRC of the SA (i.e., scrambledCRC using the predefined CRC mask for the SA corresponding to theunicast D2D MAC PDU and unscrambled CRC for the SA corresponding to thenon-unicast D2D MAC PDU).

The proposed technique can be used to indicate whether the destinationUE is in same group as the source UE by including the group indicatorfield. The proposed technique can be used to encode/decode the SRC/DSTUE ID/DST fields in case of unicast D2D MAC PDU for the unicast D2Dcommunication within the group. The proposed technique can be used toencode/decode the SRC/SRC GRP ID/DST UE ID/DST fields in case of unicastD2D MAC PDU for the unicast D2D communication across the group.

FIG. 10a illustrates a process for partitioning an N bit address spacefor generating the D2D MAC PDU format, according to an embodiment asdisclosed herein. Consider the unicast D2D communication is establishedwithin the members of the group or across groups. In this method ‘N’ bitaddress space is partitioned into two address subsets (i.e., addresssubset 1, and address subset 2). The partitioning is done such that eachaddress subset has distinct addresses. The number of addresses in eachsubset may be same or different. In an example, the partitioning of 24bit address (i.e. D2D UE ID and D2D Group ID size is 24 bits) is shownin the FIG. 10a . Each group is assigned the distinct address (i.e. D2DGroup ID) from the Address subset 2. Each group member is assigned anaddress (i.e. D2D UE ID) from the Address subset 1. The group membersare assigned address such that each member of the group has distinctaddress. The group member of the distinct groups can have same address.The advantage of this partitioning is that there is no collision betweenthe D2D UE ID and the D2D Layer 2 Group ID. In order to uniquelyidentify the UE across the groups both D2D UE ID and D2D Layer 2 GroupID needs to be transmitted in the D2D MAC PDU.

The D2D MAC PDU format is illustrated in the FIG. 10b The MAC layerprotocol in the communication unit 202 first determines whether the MACSDU(s) to be transmitted in the D2D MAC PDU is for the unicast D2Dcommunication or not. The MAC layer protocol receives information fromthe upper layers (e.g. RLC layer) along with the MAC SDU (i.e. RLC PDU)indicating whether the MAC SDU is for the unicast D2D communication orthe groupcast D2D communication. If the MAC SDU(s) is for the unicastD2D communication then, the MAC layer generates the D2D MAC PDU asfollows.

The 4 bits D2D MAC PDU format version number is included in the MACheader and is set to ‘0001’ (i.e. decimal value 1) in the MAC header ofthe D2D MAC PDU. Note that D2D MAC PDU format version number in the MACheader is same for the unicast D2D MAC PDU and the non-unicast D2D MACPDU. In an embodiment, the D2D MAC PDU format version number in the MACheader can be distinct for the unicast D2D MAC PDU and the non-unicastD2D MAC PDU.

The 4 reserved bits following the D2D MAC PDU format number is set tozeros.

The 24 bits SRC field is included in the MAC header. The 24 bits SRCfield in the MAC header of the D2D MAC PDU is set to the D2D UE ID ofthe source UE 102. The D2D UE ID encoded in the SRC field is the unicastaddress of the source UE 102 and is unique within the group.

The 16 bit DST field is also included in the MAC header. The 16 bits DSTfield in the MAC header of the D2D MAC PDU is set to 16 MSBs of the D2DUE ID of the destination UE 104.

The 24 bits SRC GRP ID field is included in the D2D MAC header. The 24bits SRC GRP ID field in the MAC header of the D2D MAC PDU is set to theD2D Layer-2 Group ID of the source UE 102. This field is included onlyif D2D UE ID of Destination UE 104 is included in the DST field.

The 24 bits DST GRP ID field is included in the MAC header. The 24 bitsDST GRP ID field in the MAC header of the D2D MAC PDU is set to D2DLayer-2 Group ID of the Destination UE 104. This field is included onlyif the D2D UE ID of the destination UE 104 is included in the DST field.

The MAC subheader(s) in the MAC header corresponding to MAC SDU(s)and/or padding is then included in the D2D MAC PDU payload.

In an embodiment, the DST GRP ID/SRC GRP ID can be included in the MACControl Element instead of MAC header.

In an embodiment, the unicast D2D communication is only allowed withinthe group, only one GRP ID is included in MAC header or MAC CE asillustrated in the FIG. 10c .

In an embodiment, the unicast D2D communication is allowed within thegroups as well as across the groups, the Group indication (GI) field canbe included to indicate whether both SRC GRP ID and DST GRP ID arepresent or only one of them is present as illustrated in the FIG. 10d .Instead of GI different value if the D2D MAC PDU format version numbercan also indicate whether both SRC GRP ID and DST GRP ID are present oronly one of them is present.

The SA including the 8 LSBs of destination UE's D2D UE ID and CRC bitsis transmitted prior to transmission of the D2D MAC PDU. In anembodiment, the scheduling assignment including the 8 LSBs ofdestination UE's D2D UE ID and with scrambled CRC bits is transmittedprior to transmission of the D2D MAC PDU. The SA is protected using theCRC. The SA information is used to calculate the set of CRC parity bits.The scheduling information bits are divided by the CRC generatorpolynomial to generate 16 CRC parity bits. The CRC parity bits are thenscrambled using the pre-defined CRC mask. The scrambled CRC is obtainedby performing the bit-wise XOR operation of the 16 bit calculated CRCparity bits and bits of pre-defined CRC mask.

The proposed method allows the receiving unit to determine presence ofGI/SRC GRP ID/DST GRP ID fields in the D2D MAC PDU if D2D UE ID isencoded in the DST field and SA information.

In an embodiment, the ‘N’ bit address space is partitioned into twoaddress subsets (i.e., address subset 1 and address subset 2). Thepartitioning is done such that each address subset has distinctaddresses. The number of addresses in each subset may be same ordifferent. In an example, the partitioning of 24 bit address (i.e. D2DUE ID and D2D Group ID size is 24 bits) is shown in the FIG. 10a . Eachgroup is assigned the distinct address (i.e. D2D Group ID) from theaddress subset 2. Each UE is assigned an address (i.e. D2D UE ID) fromthe address subset 1. Each UE (irrespective of group which it belongs)is assigned a distinct address from address subset 1. The proposedmethod avoids the collision between the D2D UE ID and the D2D Layer 2Group ID. The proposed method avoids the collision between D2D UE ID oftwo UEs.

Consider the unicast D2D communication is established within the membersof the group or across the groups. During the unicast D2D MAC PDUgeneration, the SRC field and the DST field are set to source D2D UE IDand 16 MSBs of destination D2D UE ID respectively. 8 LSBS of destinationD2D UE ID are set in SA.

FIG. 11 illustrates a computing environment 1102 implementing themechanism for discriminating the unicast D2D communication and thegroupcast D2D communication in the D2D communication, according to anembodiment as disclosed herein. As depicted in the figure, the computingenvironment 1102 comprises at least one processing unit 1108 that isequipped with a control unit 1104, an Arithmetic Logic Unit (ALU) 1106,a memory 1110, a storage unit 1112, a plurality of networking devices1116 and a plurality Input output (I/O) devices 1114. The processingunit 1108 is responsible for processing the instructions of thetechnique. The processing unit 1108 receives commands from the controlunit 1104 in order to perform its processing. Further, any logical andarithmetic operations involved in the execution of the instructions arecomputed with the help of the ALU 1106.

The overall computing environment 1102 can be composed of multiplehomogeneous or heterogeneous cores, multiple CPUs of different kinds,special media and other accelerators. The processing unit 1108 isresponsible for processing the instructions of the technique. Further,the plurality of processing units 1104 may be located on a single chipor over multiple chips.

The technique comprising of instructions and codes required for theimplementation are stored in either the memory unit 1110 or the storage1112 or both. At the time of execution, the instructions may be fetchedfrom the corresponding memory 1110 or storage 1112, and executed by theprocessing unit 1108.

In case of any hardware implementations various networking devices 1116or external I/O devices 1114 may be connected to the computingenvironment 1102 to support the implementation through the networkingunit and the I/O device unit.

The embodiments disclosed herein can be implemented through at least onesoftware program running on at least one hardware device and performingnetwork management functions to control the elements. The elements shownin the FIGS. 1 to 11 include blocks, elements, actions, acts, steps, orthe like which can be at least one of a hardware unit, a software unitor a combination of hardware unit and software unit.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the embodiments herein that others can, byapplying current knowledge, readily modify and or adapt for variousapplications such specific embodiments without departing from thegeneric concept, and, therefore, such adaptations and modificationsshould and are intended to be comprehended within the meaning and rangeof equivalents of the disclosed embodiments. It is to be understood thatthe phraseology or terminology employed herein is for the purpose ofdescription and not of limitation. Therefore, while the embodimentsherein have been described in terms of preferred embodiments, thoseskilled in the art will recognize that the embodiments herein can bepracticed with modification within the spirit and scope of theembodiments as described herein.

1-15. (Canceled)
 16. A method for device to device (D2D) communicationof a first terminal, the method comprising: generating a media accesscontrol (MAC) header comprising first information for identifyingwhether a MAC service data unit (SDU) is for a groupcast or a unicast;transmitting a MAC protocol data unit (PDU) including the MAC header andthe MAC SDU to a second terminal or a group including the secondterminal.
 17. The method of claim 16, wherein the MAC header furthercomprises second information for identifying the second terminal or thegroup, wherein if the first information indicates the MAC SDU is for thegroupcast, the second information is a groupcast identifier, and whereinif the first information indicates the MAC SDU is for the unicast, thesecond information is a unicast identifier.
 18. The method of claim 16,wherein if the first information is set to 0001, the first informationindicates the MAC SDU is for the groupcast, and wherein if the firstinformation is set to 0010, the first information indicates the MAC SDUis for the unicast.
 19. The method of claim 16, wherein the MAC headerfurther comprises third information for identifying the first terminal.20. The method of claim 16, wherein the first information is included inMAC PDU format version number field of the MAC header.
 21. A method fordevice to device (D2D) communication of a first terminal, the methodcomprising: receiving, from a second terminal, a media access control(MAC) protocol data unit (PDU) including a MAC service data unit (SDU)and a MAC header comprising first information for identifying whetherthe MAC SDU is for groupcast or unicast; and identifying whether the MACSDU is for groupcast or unicast based on the first information.
 22. Themethod of claim 21, wherein the MAC header further comprises secondinformation for identifying the first terminal or a group including thefirst terminal, wherein if the first information indicates the MAC SDUis for the groupcast, the second information is a groupcast identifier,and wherein if the first information indicates the MAC SDU is for theunicast, the second information is a unicast identifier.
 23. The methodof claim 21, wherein if the first information is set to 0001, the firstinformation indicates the MAC SDU is for the groupcast, and wherein ifthe first information is set to 0010, the first information indicatesthe MAC SDU is for the unicast.
 24. The method of claim 21, wherein theMAC header further comprises third information for identifying thesecond terminal.
 25. The method of claim 21, wherein the firstinformation is included in MAC PDU format version number field of theMAC header.
 26. A first terminal for device to device (D2D)communication, the first terminal comprising: a transceiver configuredto transmit and receive a signal; and at least one processor configuredto generate a media access control (MAC) header comprising firstinformation for identifying whether a MAC service data unit (SDU) is fora groupcast or a unicast, and to transmit a MAC protocol data unit (PDU)including the MAC header and the MAC SDU to a second terminal or a groupincluding the second terminal.
 27. The first terminal of claim 26,wherein the MAC header further comprises second information foridentifying the second terminal or the group, wherein if the firstinformation indicates the MAC SDU is for the groupcast, the secondinformation is a groupcast identifier, and wherein if the firstinformation indicates the MAC SDU is for the unicast, the secondinformation is a unicast identifier.
 28. The first terminal of claim 26,wherein if the first information is set to 0001, the first informationindicates the MAC SDU is for the groupcast, and wherein if the firstinformation is set to 0010, the first information indicates the MAC SDUis for the unicast.
 29. The first terminal of claim 26, wherein the MACheader further comprises third information for identifying the firstterminal.
 30. The first terminal of claim 26, wherein the firstinformation is included in MAC PDU format version number field of theMAC header.
 31. A first terminal for device to device (D2D)communication, the first terminal comprising: a transceiver configuredto transmit and receive a signal; and at least one processor configuredto receive, from a second terminal, a media access control (MAC)protocol data unit (PDU) including a MAC service data unit (SDU) and aMAC header comprising first information for identifying whether the MACSDU is for groupcast or unicast, and to identify whether the MAC SDU isfor groupcast or unicast based on the first information.
 32. The firstterminal of claim 31, wherein the MAC header further comprises secondinformation for identifying the first terminal or a group including thefirst terminal, wherein if the first information indicates the MAC SDUis for the groupcast, the second information is a groupcast identifier,and wherein if the first information indicates the MAC SDU is for theunicast, the second information is a unicast identifier.
 33. The firstterminal of claim 31, wherein if the first information is set to 0001,the first information indicates the MAC SDU is for the groupcast, andwherein if the first information is set to 0010, the first informationindicates the MAC SDU is for the unicast.
 34. The first terminal ofclaim 31, wherein the MAC header further comprises third information foridentifying the second terminal.
 35. The first terminal of claim 31,wherein the first information is included in MAC PDU format versionnumber field of the MAC header.